1. Field of Invention
The present invention is directed to battery-operated, autonomous data recording devices, more particularly, to low power devices that can be configured to operate on a recording schedule.
2. Discussion of Related Art
There are many applications for automated data collection. In particular, the collection of audio data in the field can be used to monitor populations of wildlife such as birds, bats, frogs and whales for presence, absence, and abundance data for specific species.
One of the greatest challenges in the deployment of data collection equipment in the field is the scarcity of power. Remote locations may not have access to power from utilities, and therefore, batteries are generally required to power data collection devices. Supplemental solar power may not be practical as solar systems tend to be heavy and expensive, and there may not be sufficient light in many installations. Weight can also be an important consideration for equipment that is moved from one remote location to the next, further limiting the size and capacity of batteries that can be used. Given the finite capacity of any battery power supply, the data recorder will only be able to operate for a limited period of time. The lower the amount of power consumed by the data recorder, the longer the recorder can operate and the more data can be collected before manual intervention (e.g. to replace batteries) is required.
One approach to extending the operating life of automated data collection systems is to configure the systems to record on a schedule rather than continuously. In most cases, the power consumed for actual data recording is significantly greater than the power consumed to remain idle during scheduled down time. This approach is especially well suited to wildlife monitoring as different species are more likely to vocalize at certain times of day. For example, many species of birds sing at dawn while many species of frogs sing after dusk.
However, conventional implementations of the above approach are not ideal as significant power is still consumed during the idle periods and the scheduling capabilities are limited. For example, referring to FIG. 1, there is illustrated an example of a conventional system discussed in an article entitled “The Use of Automated Data-Acquisition Techniques in Monitoring Amphibian and Reptile Populations,” by Charles R. Peterson and Michael E. Dorcas, Department of Biological Sciences, Idaho State University, and published on pages 369-378 in McCullough, D. R. and R. Barrett, 1992, Wildlife 2001: Populations, Elsevier Applied Science, London. According to the Peterson and Dorcas article, the system makes use of a series of interval timers 102 that trigger a relay 103 to power an off-the-shelf audio recorder 104. Power is supplied by a battery 101. One disadvantage of this system is that the relay 103 consumes extra power exceeding several milliwatts. Another disadvantage of this system is that the simple timers 102 provide limited programming flexibility. For example, the timers 102 are unable to accurately track the time of sunrise for given latitudes and times of year, to implement more complex sampling protocols, or to combine different protocols for the simultaneous monitoring of different species.
Referring to FIG. 2, there is illustrated a block diagram of a subsequent version of the system of FIG. 1. The system of FIG. 2 includes a microprocessor-based controller 202 to control power to the off-the-shelf audio recorder 104 using an efficient solid state power regulator 203. While this approach improves the programming flexibility of the system, the microprocessor-based controller consumes several milliwatts of power, even when idle.
In another implementation, an autonomous recording unit (developed by the Bioacoustics Research Program at the Cornell Lab of Ornithology) comprises an audio data recorder integrated with a controller by sharing a microprocessor. The microprocessor implements a recording schedule and directs the acquisition and storage of audio data. The integration of the data recorder and the controller represents an improvement of efficiency over the systems discussed above in reference to FIGS. 1 and 2 by reducing the number of active components in the design. However, the microprocessor remains powered during idle periods and continues to consume power.